Autogenous smelting of sulfides



Feb. 2, 1954 J. R. GORDON I'AL AUTOGENOUS SMELTING 0F' SULFIDES FiledJune 25. 1949 3 Sheets-Sheet l Jaffe-s Raya/Mfr Gama/v Feb 2, 1954 J. R.GORDQN mL 2,668,107

AUTOGENOUSSMELTING OF SULFIDES Ei'led June 25., 1949 -3 Sheets-Sheet 2Feb 2 1954 J. R. GORDGN Erm.

AUTOGENOUS SMELTING OF- SULFIDES 3 Sheets-Sheet 3 Filed June 25, 1949Patented Feb. 2, 1954 UNITED STATES PATENT OFFICE AUTOGENOUS SMELTING FSULFIDES Application June 25, 1949, Serial No. 101,336 y Claimspriority, application Canada May 13, 1949 (Cl. 'J5-74) Claims.

The present invention relatesto the art of treating nickel and coppersulfide ores, and, more particularly, to the art of autogenouslysmelting finely divided sulde ores or concentrates containing iron,nickel and/or copper for the production of matte and slag.

A well-known procedure typical of conventional practice for theproduction of nickel-copper matte and blister copper from nickel-ironsulde and copper-iron sulfide bearing ores, such as those of the Sudburydistrict, involves a flotation concentration of the ore into one or morenickel-iron sulfide concentrates (mainly pentlandite and pyrrhotite) anda high-grade copperiron sulfide concentrate (mainly chalcopyrite). Thenickel concentrate is roasted and the `resulting calcine is smelted in areverberatory furnace to obtain reverberatory matte which isbessemerized tc produce a. substantially iron-free, nickel-rich mattealso containing copper. -Silnilarly, the copper concentrate is smeltedin a reverberatory furnace, separately from the calcined nickelconcentrates, to obtain reverberatory matte which is then bessemerizedto produce blister copper. Bessemerizing the reverberatory mattesproduces nickel-rich and copper-rich slags which are treated for metalrecovery by passing through the reverberatory furnaces.

Smelting by the foregoing and other conventional procedures hasdisadvantages in that costs of heating by carbonaceous fuel orelectricity are high and in that diiculty may be encountered in securingdiscard slags as clean as desired. Various proposals have been made inthe past for the suspension or flash smelting of sulilde ores andconcentrates in order to decrease or eliminate the use of carbonaceousfuel or electric power. Thus H, H. Bridgeman in U. S. Patent No. 578,9121897) proposed ilash smelting of pulverized sulfide ore and flux in areverberatorytype furnace to produce matte and slag. Use of preheatedair for flash smelting of suldes was recommended inthe Klepinger, Krejciand Kuzell U. S. Patent No. 1,164,653 (1915).

and P. B. Bryk, in British patent applicationy 23,546/48, claim use ofair preheated by the fur- J. W. Ryselin I nace exit gases and use of adownwardly directed burner. H. Freeman in 1930 Adisclosed having flashmelted Gepest sulfide otationmcentrate.

in his U. S. Patent No. 2,209,331 disclosed a process for the productionof elemental sulfur by a reaction between sulfur dioxide and flashsmelted sulfide particles suspended Within thev sulfur 'l dioxide andmentioned the :dash smelting of sulg des containing copper or nickelwith flux and oxygen-rich gas to produce a molten bath. In

the Kaling and Brannstroin U'. S. Patent` No.

2,295,219, separate preparation of a molten iron Y sulfide product priorto its use in slag cleaning operations is disclosed. The Brannstromandsundstrom swedish Patent No. 118,492 1947) disclosed the flashsmelting of pyrite over slag wherein the free atom of sulfur in thepyrite (FeSz) is burned to assist in melting the re- A mainder of thepyrite and thus toform a spray of molten iron sulde for slag cleaningpurposes.

However, some of the above processes have serious shortcomings andothers are not applicable to pyrrhotitic nickel-containing ores.

We have discovered an improved process forthe production of matte richin nickel and/or copper, directly from nickel and/or copper conlcentrates, which involves a novel combination of operations and whichproduces concomitantly a' slag relatively 10W in nickel and/or copper.

It is an object of the present invention to pro'- vide an economicalmethod for autogenously smelting sulde ores and concentrates containingiron and nickel and/or copper to prcduce'matte or metal and a slagrelatively low in nickel and/or copper.

Another object is to provide a method of smelting sulfide ores andconcentrates containingiron, nickel and/or copper by utilizing thematerial being treated as fuel to providethe necessary smeltingtemperatures toY obtain a matte containing nickel and/or copper and,concomitantly, a slag low. in nickel and/or copper and containingacentrate oventhe slag-whereby said.slagwistwasl-iedwith a shower#ofmolten-:iron-rich matteiA dropi lets.

The present invention vcontemplates as an addi-.Vv tional objectproviding a process for autogenously smelting both nickel and/or copperdsul'de concentrates and pyrrhotite concentrate to. produce high-gradematte and low-grade slag1 .and,..cone.-

comitantly, producing gas containinghighonevcentrations of sulfurdioxide.y

Other objects and advantages will become-.ap--- parent from thefollowing descriptiontakenfinf conjunction with the drawings, in which:

Fig. 1 is a schematic diagrammi. aniembodiment of the present inventionin which a nickel and/ or copper sulfide concentrate is-autogenouslysmelted to produce nickel and/or copper-rich matte and slag rich innickel and/or copper and in which, alternatingly, Dyrrhotite concentrate10W` Ain `nickell and/or-copper antogenously` smelted intliesameiurnacettogproducea' shower of"mclten low=grade-matte and' slag which're moved-nickelland/o1" copperfrom^said-rich slag? Fig." Zdepicts`Aa-1nodirication'A of thenovelproc-A essin -vvlfxicliA the--autogenous--smelting -of both nickel-and/or coppery suldeconcentrate' andpyrrliotitelconcentrate can take placeA simulta neorusly`1 throughburners 1 locatedatv different--4 positions-'inthe same furnace,-thenickel and/or copper-richematte -being tapped vfrom the -high gradeendl@ of fsaid furnaceand the slag beingv` tapped-rom the-lowgradeorpyrrhotite end of the furnace, Wherebythe rich slag -is depleted ofnickel f and/orl copper by the low-grade matte 'f shower-andibycountercurrent-flovveof` matte relative to slag;

Fig. 3 illustrates anethenmodication ofthe processL in-whielrthefurnaceisprovided withv aL heartltpartitionon-barrier to separatethemoltenloW-grade1-mattefrom the molten high-grade matte-'butwhich permits theslag-from thehigh` grade endf of# the furnaceto -flowover-anddntotlieslow-grade end -o the furnaceior purposesofA nickelfaaid fo1=copper-recovery-from-'said slag and Figaltsl-lows `still anothermodification of" tl'iel presentlfinvention in which the preductionL ofVY' incitanl low-'grade -matteby theeautogenouslsmelt ing cihmzrrhotite`concentrate andtheshoweringw of said lovv-gradematte-onto-` themoltcnslagy ricl-r` irrnickelland/or copper occurs in a'furnace separatefromfthe furnace in which high-grade matte andfrich slag are produced.

Thepresentainvention comprises `anovel Vcom-- binationarofioperationsfor` either. simultaneously; or cyclicallyautogenously smeltingstwo,sulde materialsfof' different compositions with uxnone sulderconcentratebeing rich in. nickel and/.or copper Y and ther other. sulfideconcentrateA being, lowiin nickel and/or copper. sulfide but rich in.pyrrhotite. The novel. process utilizes the exo-v therrnic reactionsoccurring between metalsul-A ildes and gases containing asufficientlyhigh'concentration of free oxygen to autogenously smelt.saidlsuln'des andflux to produce matte and slag. or even metal and slag.

When thev present invention is ycarried into practice; it involvescoordinatedV control over various-metallurgical andmechanicalfactorsgjirr-V cludingfcompositions, absolute andl relative particlesizes and moisture contents of the sulfide concentrates and flux, thefree-oxygen contents of the burner gas and the ratios of free oxygen andsiliceous flux to sulfide concentrates, furnace dimensions, and furnacetemperatures. For in stance, great care must be taken to insure exactproportioning fandcmixinggofftheivarious components;v of' thezburnerfeedgincludinga the oxygen, and also the rate of injection thereof intothe furnace. Proper furnace and burner construction.as described.hereinafter are important in obtaining optimum operation. The ratio ofsiliceoussiiuxv.tosulde concentrate is predetermined-bythedegreelof ironsuliide oxidation desiredyaire", tlieaznount of iron oxide formed, and

tne-silicaainfthesulfidedlux mixtures must be inA-amountsuicientto forma suitable slag with tiieironoxidepro'duced.

In order to' initiate the exothermic reaction y betiveemtheiromsuldefraction of the concentrate and the free oxygen of the gas, the furnaceinto`which-the-mixture is injected must be preheatedvto over about 1500F., and preferably over about 2000a F., by means of, for example, oil,coal or gas ring.

In tliatp'art'of *theprocess'involvingthe autogencussmeltingoffhigh-grade nickel 'and/or cop*- per-sul'd'e concentrate; it is desiredthat-sufiicieni'.'V of the ironsulfide fraction be' oxidizedttoform"ironA oxide and lgaSeOuSsulur dior'iide'toA produce` the desired gradeof matte; due consideration being given to'maintenance offsuitablefurnace temperature; While-at the same Atime-it is also desired -to/have as little as possible ofthe nickeland/or.coppersuldefccncomitantly-oxidizedfintot the slag: However;separationofa majonportionof theiron; asan oxide in theslag;fromtl'ie`copper and/or'nickel matte -is not commercially feasible Without'unavoidable production of slag`- suiii-'ciently rich in nickel and/orcopper tovvarhu rant recovery therefromof these valuableelements.- Thepresent invention contemplates as an essential feature, in novelcombination withthe `aforernentionedJautogenous smelting of nickeland/or copper-suliideconcentrate; the operationY of" slagfcleaning byautogenously"smelting pyrrhotitefconcentra-te to'produce a shower'oflowgrade-matter and slag-Which falls on the aforementioned rich1 slag:

In" order` toproduceY aI low-grade,y iron-richA matte1 suitable' forslage-cleaning purposes,` and a`v portion*k offthe -pyrrhotiteconcentrate `is oxidized; in the presence of iiux; they remaining`lporti-onv` being4 melted by combustion of i the portionl oxidizedifTide-molten,L unoxidizedliron suld'efrac-- tion :oi the autogenously-smeltedX py-rrhotite con centrate xupon coming; into intimate contact:with'- the 1Yl'iigh-gradei` or: richr. slag obtained `fron-11 thenickel.- and/ or *copper* sulfide? smelting' operation recovers.-nickel; and/or copper; values: from; the; rich'slag soasto obtain asanal:product;,a1slag= impoverishein. nickel.- and/or copper. Thus;smeltingt .nickeliierous pyrrhotite in' thepresentiprocess...servesfatwoffold purpose: (lite clean.`

containing copper-rich minerals and/or nickelrich minerals and alsocontaining pyrrhotite low in copper and/or nickel. The ore aftercomminution isiirst treated by otation and, if desired, by magneticseparation operations 3 to yield (1) a pyrrohotite concentrate I3 low incopper and/or nickel, (2) one or more highgrade sulfide concentrates Ihigh in copper and/or nickel, (3) one or more other concentrates 5 fortreatment by other processes, and (4) a reject gangue tailing 4.The'high-grade nickel concentrate I0, e. g., a concentrate containingabout to about 75% pentlandite and the balance mainly pyrrhotite, or ahigh-grade taining about 75% to about 95% chalcopyrite and the balancemainly pyrrhotite, and the iron-rich concentrate I3, e. g., aconcentrate containing about 80% to about 95% pyrrhotite, are dried inoperations 6 and 1, respectively, to a moisture content of less thanabout 0.5% free moisture, preferably less than about 0.25% freemoisture.

If the concentrate is too coarse, it isl further comminuted. For bestresults, the concentrat-e is preferably at least about 95% minus 65 meshand about 50% minus 200 mesh. The suldes must be fine enough and mustremain in suspension for sufficient time to react with substantially allthe oxygen present. On the other hand, too iine a particle size causesexcessive dust losses. Satisfactory operation is obtained when smeltingconcentrates of the recommended particle size range in furnaces of theshape and size disclosed hereinafter. If the particle size of thesiliceous flux and the highgrade concentrate are such that they settleto the furnace hearth at approximately the same rate, the slag beingformed in various parts of the furnace will have a substantially uniformcomposition. An advantage of utilizing concentrated oxygen rather thanpre-heated air for autogenous flash smelting lies in the smaller volumesof gases involved and in the facilitated control of furnace temperaturewhich it permits. Such temperature control is important, both from theviewpoint of product temperatures and for the purpose of minimizingfurnace accretions.

Thus, a preferred embodiment of the invention illustrated in Fig. 1 is acyclic process involving, first, the autogenous smelting of highgradesulfide concentrate Ill rich in nickel and/or copper to produce molten,high-grade matte 23 and molten slag 24 rich in nickel and/or copper;second, the tapping of said high-grade matte only; third, the autogenoussmelting of pyrrhotite concentrate I3 to shower molten, lowgrade matteand molten, low-grade slag on the rich slag from which the iron-richmatte removes the major portion of the nickel and/or copper values toproduce a low-grade slag; and fourth, the tapping of the impoverished,lowgrade slag and, if desired, the tapping of the low-grade mattecontaining the nickel and/or copper values recovered from the high-gradeslag. Satisfactory results are also obtained when the high-grade matteis allowed to remain in the furnace during at least a portion of theslag-cleaning part of the cycle.

More specifically, the embodiment illustrated by Fig. 1 involvesintimately mixing the dry, iinely-divided, high-grade concentrate I0with a fluxing agent II such as quartzite or sand, to which may be addedsome lime or other fluxmodifying agent I2 if required. The controlledmixing of the .sulfide concentrate and the flux,

with or without a flux-modifying agent, is accomplished by means offeeders, mixer I1, and a sealing feeder I8 to eliminate uncontrolledpassage of air. When it is attempted to autogenously smelt a charge ofthe aforementioned composition using relatively pure silica flux, e. g.,quartzite containing about 95% silica, without a modifying agent and atnormal operating temperatures, a metallurgically unsatisfactory slag isusually produced and detrimental solid accretions tend to accumulate inthe furnace 22. However, addition of iiux-modifying agents I2 and i5,such as lime, magnesia or alumina, to the iiux may be omitted if asiliceous flux is chosen which already contains suitable modifyingagents. quartzite flux may require the addition of as much as 10% limeor even more, a sand containing, for instance, only about silica and thebalance mainly alumina, lime and other oxides, requires little or noadditional modifying agents. The neness of the siliceous flux is aboutminus 48 mesh and the free-moisture content is less than about 0.5%,preferably less than about 0.25%. The ratio of flux to sulfideconcentrate on a weight basis is based on the silica content of theflux, the grade of matte product desired, and the production of ametallurgically suitable slag. A suitable slag normally contains about30% to about 35% silica. In the autogenous smelting of nickel-richpentlandite concentrates or copper-rich chalcopyrite concentrates, theweight of lux amounts to between about 15% and about 40% by weight ofthe sulfide concentrate.

The sulfide-iiux-oxygen mixture is injected through one or more burners2I into a reverberatory-type furnace 22 at a furnace temperature aboveabout 1500 F., preferably between about 2100 F. and about 2300 F., bymeans of a gas containing more than about 65% free oxygen, preferably acommercially-pure concentrated oxygen containing about to about 98% freeoxygen, delivered under pressure by pipeline 20 from an oxygen plant.'I'he burners for injecting the sulde-flux-oxygen mixture into thefurnace are similar in operating principle to con- Ventionalpulverized-coal burners and are proportioned to impart a.velocity ofabout 50 to about 100 feet per second to said mixture. The furnace issimilar in shape to, but only about one-quarter the volume of,conventional reverberatory smelting furnaces per unit of solid feedrate. The burner or burners are located in the end wall-and are directedin a substantially horizontal direction. A slightly downward inclinationof the burner has been found valuable in avoiding the formation ofaccretions on the furnace bottom.

A suiiicient proportion of free oxygen is used to yield a matte 23containing between about 15% and about 65% total copper and nickel. Theoxygen necessary to promote the reaction to the desired degree ofoxidation and to obtain the desired furnace temperature is broadlybetween about 15% and about 35% by Weight of the sulfide concentrate andis controlled by a valvemetering device 25. When smelting concentratesin the normal otation size range, the free oxygen present is almostentirely consumed. The molten matte 23 and the slag 24 are attemperatures within the range of about 2000 F. to about 2300" F.Autogenous smelting under the foregoing.conditionsusually produces richslag 24 containingV about 30% Yto aboutl 35% silica Thus, while asilica-.

ing example is given, illustrative of the embodiment shown by Fig. 1:

A copper-nickel-iron sulfide ore, of the type occurring near Sudbury,Ontario, Canada, is treated by flotation and by magnetic separation toyield (l) a reject gangue tailing; (2) aY nickeliferous pyrrhotiteconcentrate containing about 0.05% copper, about 0.90% nickel, aboutsiliceous gangue and the balance iron and sulfur; (3) one or more nickelconcentrates containing about 0.5% to about 1.5% copper, about 3% toabout 20% nickel and the balance mainly iron, sulfur and silceousgangue; Y and finally (4) a copper sulfide concentrate containing about30% copper, about 1% nickel, about 3% siliceous gangue and the balancemainly iron and sulfur. The copper sulfide flotation concentrate isfiltered, dried to a moisture content of less than about 0.5% andcomminuted to substantially all minus 65 mesh by milling in closedcircuit vvith an air classifier. Siliceous flux and lime are dried toless than about 0.5% free moisture content and are comminuted to minus48 mesh.

The dried, finely-divided, copper sulde concentrate and fluxes are fedfrom bins at care-- fully controlled rates, mixed, and then fed to aburner of the type mentioned hereinbefore. Commercially pure oxygen,containing about 95% oxygen, carries the mixed, finely-divided solidsthrough the burners into the hot flashsmelting furnace where iron andsulfur in the sulfide concentrate are burned in suspension in the oxygento form iron oxides and sulfur dioxide. The iron oxides, vsiliceous uxand lime combine to form a fiuid slag. This combination occurs partlywhile the material is still in suspension and is completed after itsettles by gravity to the furnace hearth. The unburned, or partlyburned, sulfides settle upon the hearth and form a molten matte layerbeneath the slag.

After a period of time, smelting of the copper concentrate isdiscontinued, matte is tapped, and then smelting of the aforementionedpyrrhotite concentrate is commenced, using a procedure parallel to thatdescribed for the copper concentrate. After smelting pyrrhotite for aperiod of time about '15% to about 30% aslong as the time during whichlthe copper concentrate was smelted, slag is skimmed and the 4-partcycle is then repeated.

The sulfur dioxide gas passes from the furnace to the settling chamber,together with gaseous impurities present in the commercial oxygen anddust which amounts to about 5% of the solids charged into the furnace.Exit gas from the settlinnr chamber, containing about 1% of the vfurnace solid charge, is then cleaned `by passage through an open spraytower, a wet cyclone, mineral fibre bags, and finally a wetCottrell. Thedust leaving the wetA cyclone amounts to less than 0.05% of the furnacesolid charge. The greater part of the SO2 in the gas is then liquefiedby methods known in the art.

The proportion of oxygen to sulfides is adjusted to yield a mattecontaining about 55% to about total copper and nickel. The weight ofoxygen used is about v25% to about 35% of that of the copper suldeconcentrate smelted. The proportion of siliceous iiux used is about 25%to about 35% of the copper sulfide concentrate and is sufficient to formslag containing about 31% to about 33% silica. v

SpecificY average results obtained over a representative one-week periodof continuous testing 10 using the foregoing combination of operationsare as follows:

Copper sulfide concentrate, averaging 30.6% Cu, 1.1% Ni, 33% S and 1.8%SiOz, was fiash smelted as described above using as flux sand amountingto 33.1% by Weight of the copper sulfide concentrate. 'The sandcontained 80% silica, and 5% of lime was added thereto. The amount ofoxygen used amounted to 33% of the concentrate smelted. After each 6hours of this first operation, matte averaging 57.65% Cu and 2.03%

Ni was tapped (second operation). The slag produced by the aboveoperation contained about 0.90% Cu and about 0.15% Ni. 'I'he coppersulfide concentrate smelting was then discontinued and low copperpyrrhotite concentrate averaging about 1% Ni, 57% Fe,A 35% S and 2%'SiOz was then fiash smelted (third operation), using approximately thesame ratio of fiux and oxygen as was usedin smelting the copper sulfidecone centrate. This operation was continued for 1 hour and provided ashower of low-grade matte and slag droplets. The matte droplets removeda large proportion of the copper and nickel from the slag to theunderlying low-grade matte. The pyrrhotite used in this cycle amountedto 30% of the copper sulfide concentrate smelted. At the end of thisoperation, slag averaging 0.35% Cu, 0.16% Ni and 34.8% Si02 was skimmed(fourth operation). This cycle was then repeated.

Treatment of several thousand tons of copper sulfide concentrate and ofnickel sulfide concentrate by the foregoing process showed that cost ofthe oxygen required to flash-smelt the various concentrates was aboutone-half that of the cost of the coal which would have been-required tosmelt the same material by conventional meth-l ods.y Furthermore,refractory consumption was reasonable and was indicated to be less thanin conventional practice. The furnace exit gas contained sulfur dioxideby volume and was cleaned, condensed by compression and cooling, and theresulting liquid sulfur dioxide used successfully in the commercialproduction of sulte wood pulp. Smelting of copper sulfide concentrate ofthe same composition by conventional coal-fired reverberatory furnacepractice under similar conditions would yield matter of much lower gradewithout significant compensation in lower slag loss. Data averaged fromfiash-smelting of nickel sulfide concentrate are as follows: Nickelconcentrate, averaging 1.88% Cu, 11.95% Ni,.was flash-smelted using asfiux about 20% by weight of quartzite together with 2.5% by weight oflime. The amount of oxygen used amounted to 26.5% rby weight of'suldessmelted. After each 6 hours of operation, the matte averaging 6.95% Cuand 33.77% Ni was tapped, the nickel sulfide concentrate smelting wasdiscontinued, Aand pyrrhotite concentrate averaging 1.25% Ni was flashsmelted using approximately the same ratio of fiux and oxygen as wasused in the smelting of the nickel sulfide concentrate. This operationsprayed low-grade matte and slag intol the rich slag (containing about0.15% Cu and 0.60% Ni) already in the furnace; and copper and nickelwere removed from the slag layer into the under- Y lying matte, thusdecreasing the loss of valuable metal in the slag. After 2 hours of thislatter operation, the slag, averaging 0.12% zCu, 0.30% Ni and 32.3%SiO2, was skimmed. The cycle was then repeated. Y Y 'v Furnaces employedfor flash smelting'by the lpresent process differ in several respectsfrom YITI conventional reverberatory furnaces.- Surfaces exposed to thename are constructedifor example, of hard-burned -br-iclrrich'inymagnesia andrare backed by heat 'insulating material'. An: impermeableshell",r foriinstanceg-sheet steel',` normally'l entirely encloses'v'the furnacefapart from the `necessary openings lfo'r' the burners and-for withdrawing m'atteyslag,` and gasess This im= permeable casinghasbeenffound necessaryto avoid, on theone hand, leakageoffconcentratedsulfur dioxide gas -iromlth'e furnace, or,v onthe other hand;yinfiltration-lof air with" a resulting loss in thermal 'eiciencyand a`lowering 'in concentration ofv the-sulfur dioxide in the'exit gases. WeAhave found that -a -furnaceinside volume of approximately Sito-16cm ft.is requiredper ton of cold chargef'smelted per day. This isonlyaboutone-quarterth'e volume orar-conventional reverberatoryfurnaceofsimilar smelting capacity.v While some variation inthis' facton vcan beaccomplished byadj'ustment iny the/thermal insulation of theiur-naceran'd' in 'the proportion of= inert material added;v such asfux; any @wide deviation from* thefforegoing furnace A'volume rangewillv result either vin: excessive `fheat loss if the furnace-istoolargeforin rapidfailure-oi the refractories if thefurnaceisf-toofsmall'Burners for introduction of thefmixturefofsulfide, ux and oxygen areproportioned' to yield? a' velocity to said mixture ofi r`about "50tof1100` feet per:l second;` When oxygenated airis used `in'place ofcommercially fpure oxygen; the-burner exitvelocityf may be less than'that imentionedfbefcre:

In the presentY Y specification t andappended claims -where lthertermhighs-grade 'is f used in connection withY matta s'lag or` tconcentrateitismeant thereby that said-"matte, slagor. concentrate `is relativelylrich'in niolqeland/ or copper, e: g., thematte contains atl-least?about'v 15% total nickel and/orA copper, 'the concentrate kcon-'- tainsat least-about?) totalini'clcel and/or copper, andthe .slag contains at'leastf about i055 nickel and/or copper, respectively:v Converselyywherethe term -low-grade"is used in connectionJwith matte;' slagor"`concentrate;. it is Imeant thereby that said" matte;v slag 'orconcentratefis poor'inI-nickel and/or copper; e; g., the' matte,concentrate-and slag: contain;v respectively; less than theaforementionedamountsrof 'copperand/ or f nickel. In the '-'appen'dedfvclaims, 1 where the termfniclrel and copper andnickel'copper Aare used-,it ismeant to :include cases wherether'product i described; such Aas=sulde vconcentrate 'from copper-nickel-ores or'matte'; vcontainsupftorabout lllftimes asfmuch of. one fofthese metals-ias .of theother.`Where-'the term 4dnickeldis usedfthis is falsomeant toiincludefcobaltzVAlthough theA present inventionhas-been describedin conjunction.withcertainzpreferredfembodiments,` thereof,` thosef'sklled :intlie iartwill understand" that variations. andi; modifications thereof canlbemade?" Suchvariationsand modi- *about-.o5 L73, a siliceous flux and anoxidizing SES containing-about 65%tof aboutA 98 free` oxygen to obtain ahigh-grade moltenfmattef containing aemajor fportion 'of-"copper, ahigh-grade .molten siliceousslag ric'hin copper, and a gas sufficientlyrichin' sulfur dioxide as -to be suitable for direct liquefactionbycompression; autogenously smeltingfaboveabout I2G00?? lik'a mixture oflow-grade sulde concentrate lhaving a freey moisture content lessthanabout-0.5% and containingabout toabout 95% pyrrhotite, asiliceous fluxand an oxidizinggas `containingab'out 65% to about 98%freeoxygentofoxidize amajor portion of said low-grade concentrate toproduce molten lowgrade matte, rich iniron sulde; and molten lowgradeslag; showeringsaid molten low-grade matteasmolten droplets-upon saidhigh-grade molten siliceous slag tofpass through the same and to removetherefrom'the'bulk of the vcopper values to producean--enriched'mattmtapping at one point the high-grade matteprior to completion oftheautogenoussmelting of the low-grade concentrate; tapping'atanother pointimpoverished slag' in such' manner 'that the-matteand slag areseparately tapped in counter-current now-relative-'tol each other; andwithdrawing from the space above'saidmoltenslag andv molten matte gassufficiently rich iirsuliur dioxide Yas Yto be suitable for 'directliquefactionby compression.

2. Animproved process'for producing a highgrade matte, a low-gradeslag'anol gas sufciently richV in sulfurdioxde as to be'suitable fordirect liqueiacti'on by1` compression' which comprisesautogenouslysmelting'amixture of siliceous lux, an'oxidizinggascontainingabout 65% to about 98% free oxygenand'a high-grade suldeconcentrate containingl about '75% to about 95% chalcopyrite and havingaifree moisture content of less thanabout0.5% in rvarefractory-linedvimpermeably'encased chamber .being at a temperature 'aboveabout2000215.; havingports for withdrawing matte and slag and..for'exhaustinggas and)haying'at'leastl one burner for injecting said mixture to obtaina high-.grade moltenmatte rich in copper; a high-grade siliceous slagrichincopper, and argas su'icientlyirich in sulfur dioxide as tobesuitable for direct liqueiaction by compression; 'autogenouslysmeltingamixture of asiliceous flux, a low-grade sulde concentrate having a`free .moisture content. of less than about 0.5% and containingabout'80% to about 95% pyrrhotite,4 and an oxidizing gas containingabout 65% lto about 98%' free oxygen in amountssufrlcient to oxidi'zeabout 4one-fourth to about twothirds by weight ofsaid low-gradeconcentrate by injecting tl1e..lowgrade mixture .into said chamberbymeansof at least oneburner to `produce molten low-grade matte, richiniron sulde, andn low-.grade slag, said burner being directedto showersaid molten low-grade matte in .the formof. molten ldroplets.upon-saidhigh-grade molten siliceous-slag to pass Vthrough the same to removetherefrom the bulk ofthe coppervalues and'to producelanenrichedlnatteandan impoverishedslag; Ywithdrawing enrichedmatteand `impoverished slag;and withdrawing through` the gas exhaust port,gas suicientlyriclr insulfur dioxide .as .to be suitable for direct liquefaction bycompression.

3. An improved process forproducing a highgrade matte, low-grade slagand gassuiliciently rich in sulfur dioxideas'to'be suitable for directliquefaction by compressionY which comprises autogenously smelting aboveabout ()u F. a mixtureof highgrade sulfide concentrate containing'about"7r5'% torabout 95% chalcopyrite, a

13 siliceous flux and an oxidizing gas containing about 65% to about 98%of free oxygen to obtain a high-grade molten matte rich in copper, ahighgrade molten siliceous slag rich in copper, and a gas sufficientlyrich in sulfur dioxide as to be suitable for direct liquefaction bycompression; autogenously smelting above about l500 F. a mixture oflow-grade concentrate containing about 80% to about 95 pyrrhotite and atleast one sulde of the group consisting of nickel sulfide and coppersulde, a siliceous ux and an oxidizing gas containing about 65% to about98% free oxygen in an amount suiiicient to oxidize about one-fourth toabout two-thirds by weight of said low-grade concentrate to producemolten lowgrade matte, rich in iron sulfide and low in at least oneelement of the group consisting of nickel and copper, and low-gradeslag; showering said molten low-grade matte as droplets upon saidhigh-grade molten siliceous slag to pass through the same and to removetherefrom the bulk of the nickel values tc produce an enriched matte andan impoverished slag; withdrawing enriched matte and impoverished slag;and withdrawing from the space above said molten slag and molten mattegas sumciently rich in sulfur dioxide as to be suitable for directliquefaction by compression.

4. An improved process for producing a highgrade matte, low-grade slagand gas suiiiciently rich in sulfur dioxide as to be suitable fordirectliquefactionA by compression rwhich comprises autogenously smeltingabove about 2000 F. a mixture of substantially dry, finely-divided,highgrade sulde concentrate containing morethan 3% copper in the form ofsulde and the balance essentially iron sulfide, a siliceous fluxamounting to about 15% to about 40% by Weight of said high-gradeconcentrate and an oxidizing gas containing about 90% to about 98% freeoxygen amounting to about 15% to about 35% by weight of said concentrateto obtain a high-grade molten matte rich in copper and a gassuiliciently rich in sulfur dioxide as to be suitable fordirectliquefaction by compression; autogenously smelting above about 2000 F. amixture of substantially dry, finely divided, low-gradesuliideconcentrate consisting essentially of iron sulde, a siliceous uxamounting to about 15% to 40% by weight of said low-grade concentrateand an oxidizing gas containing between about 90% to about 98% freeoxygen in amounts suiicient to oxidize between about one-fourth to abouttwothirds by weight or said low-grade concentrate to produce moltenlow-grade matte, rich in iron sulfide, and low-grade slag; showeringsaid molten low-grade matte as droplets upon said high-grade moltensiliceous slag to pass through the same and to remove therefrom the bulkof the copper values to produce an enriched matte and an impoverishedslag; withdrawing enriched matte and impoverished slag; andwithdrawingfrom the space above said molten slag and molten matte gassufciently rich in sulfur dioxide as to be suitable for directliquefaction by compression.

5. An improved process for producing highgrade matte, low-grade slag,and gas sufliciently rich in sulfur dioxide as to be suitable for directliquefaction by compression which comprises autogenously smelting aboveabout 2000or F. a mixture of high-grade sulfide concentrate containingabout 10% to about 75% pentlandite and having a free moisture contentless than about 0.5%, a siliceous flux and an oxidizing gas containingabout 65% to about 98% free oxygen to obtain a high-grade molten matterich inv 14 nickel, a high-grade molten siliceousslag rich in nickel,and a gas suiiiciently rich in sulfur dioxide as to be suitable fordirect liquefaction by compression; autogenously smelting above about2000 F. a mixture of low-grade sulfide concentrate having a freemoisture content less than about 0.5% and containing about to about 95%pyrrhotite, a siliceous iiux and an oxidizing gas containing about 65%to about 98% free oxygen in amounts sumcient to oxidize about one-fourthto about two-thirds by weight of said low-grade concentrate to producemolten lowgrade matte, rich in iron sulfide, and low-grade slag;showering said molten low-grade matte as molten droplets upon saidhigh-grade molten siliceous slag to pass through the same and to removetherefrom the bulk ofthe nickel values to produce an enriched matte;tapping at one point the high-grade matte prior to completion of theautogenous smelting of the low-grade concentrate; tapping at anotherpoint impoverished slag in such manner that the matte and slag areseparately tapped in countercurrent ow relative to each other; andwithdrawing from the space above said molten slag and' molten matte gassuiciently rich in sulfur dioxide as to be suitable for directliquefaction by compression.

6. An improved process for producing a highgrade matte, low-grade slagand gas sufciently rich in sulfur dioxide as to be suitable for directliquefaction by compression which comprises autogenously smelting aboveabout 1500" F. a mixture of high-grade sulfide concentrate containingabout 10% to about 75% pentlandite, a siliceous Iiux and an oxidizinggas containing about 65% to about 98% free oxygen to obtain a high-grademolten matte rich in nickel, a highgrade molten siliceous slag rich innickel, and a gas suiciently rich in sulfur dioxide as to be suitablefor direct liquefaction by compression; autogenously smelting aboveabout 1500 F. a mixture of a low-grade concentrate containing about 80%to about 95% pyrrhotite and at least one sulde of the groupconsisting'of nickel sulde and copper sulde, a siliceous flux and anoxidizing gas containing about 65% to about 98% free oxygen in an amountsuicient to oxidize about one-fourth to about two-thirds by weight ofsaid low-grade concentrate to produce molten low-grade matte, rich iniron sulde and low in at least one element of the group consisting ofnickel and copper, and low-grade slag; showering said molten low-gradematte as droplets upon said high-grade molten siliceous slag to passthrough the same and to remove therefrom the bulk of the nickel valuesto produce an enriched matte and an impoverished slag; withdrawingenriched matte and impoverished slag; and withdrawing from the spaceabove said molten slag and molten matte gas sufficiently rich in sulfurdioxide as to be 'suitable for direct liquefaction by compression;

'7. An improved process for producing a highgrade matte, low-grade slagand gas sufliciently Vrich in sulfur dioxide as to be suitable fordirect liquefaction by compression which comprises autogenously smeltingabove about 2000 F. a

mixture of substantiallydry, nely divided, highf grade sulfideconcentrate containing more than 3% nickel in the form of sulfide andthe balance essentially iron sulfide, a siliceous ilux amounting toabout 15% to about 40% by weight of said high-grade concentrate and anoxidizing gas containing about to about 98% free oxygen amounting torabout 15% to about 35% by weightf` of z said-concentrate to obtain i a.highgrade moltenzmatte-ricnfincnickeh ahhh-.grademoltencsiliceous:slaggriclr in ,-nickel, and -a gas suficientlyrichinsuliursdioxideas to be suitable* for direct= liduefaction bycompression; autogenously; smelting` above about 20009- r".A a mixtureoi- .substantially dry, `iinely f divided, lowgrade @sulfide concentrateconsisting essentially of iron sulfide, asiliceousflux amounting toabout to140% by weight-ofsaidffloW-grade concentrate -and anroxidizinglgas containing between about 90% toabout=98% free oxygen. in amountssuicient to oxidize between4 about one-fourth to about two-thirds byweight of said low-grade concentrate tozproduce molten loW-gradematte,richain iron-sulfide, andzlow-grade slag; showering said molten;Alow-gradematte as droplets upon saidhigh-grade;molten'siliceous slagto'pass through the, same and. to removethereirom the bullo-oflthe-'nickel-values tozproduce an enriched matte' and 1any impoverishedslag Y withdrawing enriched matte and'` impoverished slag; andwithdrawing-from-the- Vspace abovev said molten slag-"and moltenrzmattegas suiiiciently rich .in sulfur dioxide `as tobe suitable for-directlliquefactionr by compression.V

8. ern-improved processior-'produoing a highgradefmatte; low-gradc-slagandi gas suiieiently rich rin sulfur-dioxide-as ytobesuitable for directliquefaction bye-impression which comprisesautogenously .smeltingabove-about 2000" F; e *c :rture ofsiliceous fiumian oxidizing gas contaning about 65 fitto about 98% ireeoxygen, and a highgrade metalv sulde'concentrate comprising at least one sulfide 'selectedfron'i thegr-oupconsisting of copper sulfide. andrnicliel 'suliide `and the balanceessentially ironfandisulfnrxin the form of sulfide, said coppersulfidecorrespondihg to a concentrate having 'betweenlzabout750/21 toabout chalcopyrite and said nickel 'sulde `corresponding to aconcentrate-having between aboutl and about'75% pentlandite,v tocbt-aina high-grade molten matte rich in at least one metal of the groupconsistingfofnickel andcopper; a grade molten -siliceous slag rich in atleast one metal of the group consisting of nichel and copper and a gassuicientlyrich in vsulfur dioxide as to be suitable for directliquefaction by compression; autogenously smelting above about 2000 E amixture of 'a siliceous flux, a low-grade sulfide concentrate containingabout'80% to about '95% pyrrhotit'e and an oxidizing gas containingbetween about 65% to about 98%free oxygen in an amount sufficient to-oxidize between about onefourth to about two-thirds by weight of saidlou-- grade concentrate to yproduce moli? matte, richl in iron sulfide;and i showering said 'molten lw-gradexnt. te as droplets upon saidhigh-grade molten siliceous slag to pass'through the same-and to removetherefrom-the 'buik of vthenietal values from the s consisting of nickeland copper to produce an enrichedA matte and; an impoverished slag;withdrawing enriched matte and impoverished slag; and withdrawing fromthe space above said molten slag-and molten matte gas-suniciently richin sulfury dioxide as to be suitable for direct liquefaction bycompression.

9. An improved processforproducing a highgrade matte, low-grade slag andgas sufficiently rich in sulfur dioxide-as toV be suitable for direct1iduefaction by compression which comprises autogenously smeltingV amixture of -siliceous flux, anv oxidizing' gas containing about 65%toabout 98% free oxygen and a -high-grademetal sulfide concentratecomprising, atr .least v onev suliide fsclected from the groupconsistingof copper. sulndc and nichel sulide and the balanceessentially `iron andsulfur in the :forni of sulfide, said copper sulde corresponding to aconcentrate having between about to about 95% chaicopyiteand said nickelsulfide corresponding to a concentrate having between about 10% andabout 75% pentlandite, in a refractory-lined iinpermeably encasedchamber being at a temperature above about 1500" F., having ports forwithdrawing matte and slag and for exhausting gas and having at leastone burner Afor injecting said mixture to obtain a high-grade moltenmatte rich in at least one metal of the group consisting of nichel andYcopper, aihigh-grade molten siliccous slag rich in at least one metal ofthe group consisting of nickel and copper and gas suiiiciently rich insulfur dioxideas to be suitable for direct liquefaction by compression;autogenously smelting a low-grade mixture of siliceous flux, a lowgradesulfide cono-entrate consisting essentially of iron sulde, and anoxidizing containing about 65% to about 98% free oxygen to oxidizebetween about one-fourth to about two-thirds by weight of said low-gradeconcentrate by injecting said low-grade mixture into said chamber bymeans of at least one burner to produce molten .low-grade matte, rich;in iron suliide, and lowgrade slag, said burner being directed to showermolten matte inthe form .of moltendroplets upon said high-grade molten.siliceous` slag to pass through the-same and. to remove therefrom thebulk, of the metal valuesfrom the group consisting of nickel and :coppertoproduce an enriched matte and an impoverished slag; withdrawingenriched matte Aand impoverished slag; and withdrawing through the-gasexhaust port gas sufficiently rich in sulfur dioxide as to-be suitablefor direct liquefaction by compression.

10. An improved process for producing a highgrade matte, low-grade slagand gas'suliciently rich in sulfur dioxide kas to be suitable for directlio'uefaction by compression which comprises autogenouslysmeltingamixture of siliceous dus', an oxidizing gas containing more than about65% free oxygen; and high-grade metal sulfide concentrate containingmore than 3% of at least one elementA from the group consisting of.nickel and copper and the balance essentially iron and sulfur inthe formof sulde-to obtain a high-grade molten. matte rich in at least Ionemetal of the group consisting ofnickel and copper, a highgrade moltensiliceous #slag rich in at least one metal of the group consisting of.nickel and copper andra gas suicientlyrich in sulfur dioxide as to besuitable for direct liquefaction by cornpression; autogenously smeltinga. mixture of low-grade sulfide concentrate consisting essentially ofiron suliide, a siliceous uxlvand an osidizing gas containingrmore thanabout S5 free oxygen in an amount. suicientto oxidize about one-fourthto about two-thirds by weight oi said low-grade concentrate to producemolten lowgrade matte, rich in iron sulfide, and low-grade slag;showering said molten low-grado matte as droplets upon said high-grademolten siiceous slag to pass through the same and to remove therefromthebull; of the metal values :from the group consisting of nickell andcopper to an enriched matte and' an impoverished slag; withdrawing-`enriched matte and improverished slag; and Withdrawingfrom Athevspace'above said ymolten slaglandA molten matte-gas sufficiently richin sulfur dioxide as to be suitable for direct Number liquefacton bycompression. 948,468 JAMES ROYCROFT GORDON. gg GEORGE HUGH CHARLESNORMAN. 5 1416262 PAUL ETIENNE QUENEAU. 1650907 WILLIAM KELVIN SPROULE.1729408 CHARLES EDWARD YOUNG. 1,850,025 References cited in the me ofthis patent 10 gfggg UNITED STATES PATENTS 11958581 Number Name Date2,035,016 '782,123 Garretson Feb. 7, 1905 2,221,620 900,466 BaggaleyOct. 6, 1908 2,510,352

18 Name Date Fink Feb. 8, 1910 Klepnger et al Dec. 21, 1915 Cavers Mar.12, 1918 Butler et al May 16, 1922 Prince Nov. 29, 1927 Wagstai Sept.24, 1929 McGregor Mar. 15, 1932 Krejc June 27, 1933 Bacon et a1 Jan. 2,1934 Kennicott May 15, 1934 Smcox et a1 Mar. 24, 1936 Wagsta Nov. 12,1940 Sklenar June 6, 1950

10. AN IMPROVED PROCESS FOR PRODUCING A HIGHGRADE MATTE, LOW-GRADE SLAGAND GAS SUFFICIENTLY RICH IN SULFUR DIOXIDE AS TO BE SUITABLE FOR DIRECTLIQUEFACTION BY COMPRESSION WHICH COMPRISES AUTOGENOUSLY SMELTING AMIXTURE OF THE SILICEOUS FLUX, AN OXIDIZING GAS CONTAINING MORE THANABOUT 65% FREE OXYGEN AND HIGH-GRADE METAL SULFIDE CONCENTRATECONTAINING MORE THAN 30% OF AT LEAST ONE ELEMENT FROM THE GROUPCONSISTING OF NICKEL AND COPPER AND THE BALANCE ESSENTIALLY IRON ANDSULFUR IN THE FORM OF SULFIDE TO OBTAIN A HIGH-GRADE MOLTEN MATTE RICHIN AT LEAST ONE METAL OF THE GROUP CONSISTING OF NICKEL AND COPPER, AHIGHGRADE MOLTEN SILICEOUS SLAG RICH IN AT LEAST ONE METAL OF THE GROUPCONSISTING OF NICKEL AND COPPER AND A GAS SUFFICIENTLY RICH IN SULFURDIOXIDE AS TO BE SUITABLE FOR DIRECT LIQUEFACTION BY COMPRESSION;AUTOGENOUSLY SMELTING A MXITURE OF LOW-GRADE SULFIDE CONCENTRATECONSISTING ESSENTIALLY OF IRON SULFIDE, A SILICEOUS FLUX AND ANOXIDIZING GAS CONTAINING MORE THAN ABOUT 65% FREE OXYGEN IN AN AMOUNTSUFFICIENT TO OXIDIZE ABOUT ONE-FOURTH TO ABOUT TWO-THIRDS BY WEIGHT OFSAID LOW-GRADE CONCENTRATE TO PRODUCE MOLTEN LOW-